With the development of optical communication technologies, optical modules are applied more and more extensively. Common optical modules include: small form factor (Small Form Factor, SFF for short), small form-factor pluggable (Small Form-factor Pluggable, SFP for short), enhanced small form-factor pluggable (Enhanced Small Form-factor Pluggable, ESFP for short), and single fiber bi-directional optical modules.
Functionally, the SFF is similar to the SFP. FIG. 1a is a schematic diagram showing an application manner of existing SFP, ESFP, and SFF optical modules in a transport system. As shown in FIG. 1a, a transmission fiber is separated from a receiving fiber, and Lucent connector (Lucent connector, LC) fibers are used. The difference lies in that: the SFF is fixed, and is used after its pins are fixed, and does not support hot-plugging, while the SFP supports hot-plugging. Basic functions of the ESFP are similar to those of the SFP. However, compared with the SFP, the ESFP has monitoring functions for performance such as the current and voltage of the optical module.
Because the transmission fiber and the receiving fiber are separated, the foregoing several optical modules all waste fiber resources; furthermore, because the transmission fiber and the receiving fiber are separated, asymmetric compensation of fibers is required in a time synchronization application.
Compared with the SFP, ESFP, and SFF optical modules, the single fiber bi-directional (Single Fiber Bi-directional SFP) optical module occupies far fewer fiber resources. The single fiber bi-directional optical module uses an LC fiber for both transmitting and receiving, supports hot-plugging, and supports monitoring functions for performance such as the current and voltage of the optical module. FIG. 1b is a schematic diagram showing an application manner of existing single fiber bi-directional optical modules in a transport system. As shown in FIG. 1b, a single fiber bi-directional optical module may use different wavelengths in a same fiber to establish two channels that do not interfere with each other: channel_1 and channel_2.
However, in the single fiber bi-directional optical modules, the optical modules at a transmitting end and a receiving end must be used in pairs. For example, the wavelength of a transmitting channel of a local optical module A is 1310 nm, and the wavelength of a receiving channel thereof is 1490 nm; if a peer optical module B is used in pairs with the local optical module A, in the peer optical module B, the wavelength of a transmitting channel needs to be 1490 nm, and the wavelength of a receiving channel needs to be 1310 nm.
Therefore, the existing single fiber bi-directional optical modules may have some problems. For example, because two optical modules communicating with each other are generally not in the same place, it is necessary to pair the optical modules during port fiber installation, and confirm whether pairing and interconnection are successful. When the more the optical module pairs are, the more complex the installation is, and the more easily errors occur. Hence, reliability of installation is reduced, and installation and maintenance costs are increased.